I’ve just finished The Grand Palace as Emily without killing anybody (as confirmed by the kill count at the end of the mission). Despite this, I encountered several dead people in the Palace itself; there may have been more but I distinctly remember three:
A dead lady in the maze-like shrubbery between the Palace and the sea shore, near to a man and a woman playing a game involving hitting a bucket with balls (but hidden from their view).
A dead man lying in his own (?) blood on the floor at the steps in the throne room.
A dead woman in a somewhat secluded room lying on a round divan in the company of two other women. Just next to her there’s a bone charm.
This isn’t counting the two dead criminals who have been used for target practice by some of the Nobles.
I understand that I am arriving just after a rather lavish party and there are many drunk and sleepy revellers about. But why are some dead? Who/what killed them? As far as I can tell they were dead when I arrived — I didn’t trigger their deaths in any way. And — except for the third one — I cannot find any mention of the dead people online, in walkthroughs etc., and they seemed very out of place in an otherwise excellently designed level.